What is rooftop greening?

For successful rooftop greeningPoints and
Important points to note during construction

The recent heat island effect, the reduction of urban green spaces, and inland flooding caused by sudden heavy rains are affecting cities, and the living environment is deteriorating. At the same time, there is a need for sustainable urban development, such as securing green spaces and creating natural environments. Rooftop greening is an effective solution to these problems, and is expected to have many benefits in the coming decarbonized society.

Here we will introduce the effects of rooftop greening, design points, and points to be careful of during construction.

The effects of rooftop greening
Rooftop greening planning/design points
Important points to note when installing rooftop greenery
Maintenance of rooftop greenery
KYODO KY-TEC's strengths and product lineup

The effects of rooftop greening

The benefits of a green roof include:

Effect 1: Energy saving effect

Rooftop greening is expected to have an energy-saving effect.

Planted area → Plants block direct sunlight and have a cooling effect due to water evaporation from the leaves
Soil → Heat insulation effect of soil material and cooling effect due to evaporation of water
Drainage layer → heat insulation effect

In comparison to the general midsummer daytime fluctuations in outside temperature and rooftop structural surface temperature, the temperature of the soil under the greened areas remains relatively low and stable, which can be expected to reduce air conditioning load and thus save energy.

Effect 2: Creating a relaxing and comfortable space

Greenery has a healing effect on people. It is also expected to have a calming effect on the mind and help relieve fatigue, and is often used in stress relief therapy. Taking advantage of these effects, schools and hospitals in particular are increasingly planning to install green roofs. Green roofs add warmth to inorganic architectural structures, and give them harmony and a sense of unity with their surroundings, a sense of presence, and a sense of vitality, and can be said to be the foundation for future urban development.

An example of a garden-style rooftop greenery
Example of greening a factory's folded-plate roof

Effect 3: Preventing deterioration of buildings

Depending on the location, the surface temperature of a building's rooftop can exceed 50°C in midsummer and drop below 0°C in midwinter. Temperatures can also vary by 1-20°C throughout the day. In addition to temperature, rooftops are also directly affected by ultraviolet rays and other direct sunlight, as well as strong winds, sand, dust, rain, snow, flora and fauna, and are also subject to changes such as repeated cycles of dryness and humidity. Installing a green roof protects the waterproof layer on rooftops that are directly exposed to these environmental pressures, helping to prevent deterioration over the long term.

Effect 4: Contribution to biodiversity

Installing rooftop greenery can create a habitat for living organisms. Recently, rooftop greenery has been used to protect endangered species of plants in the area by planting them on rooftops, and to provide a habitat for a variety of living organisms by creating ponds on rooftops, thereby maximizing the contribution that it can make to biodiversity.

Examples of biotopes
Examples of vegetable gardens and rice paddies

Effect 5: Mitigation of the heat island effect

The heat island phenomenon, in which temperatures in cities are higher than those in the surrounding areas, can be prevented by installing rooftop greenery, which is said to prevent heat accumulation on rooftops and generate evaporative heat through the transpiration effect of rooftop greenery, thereby lowering urban temperatures.

If all possible flat roofs in Tokyo's 23 wards were greened, the maximum summer temperature would drop by up to 1.4°C (calculated by the Organization for Urban Green Technology Development).

Effect 6: Increased asset value

Installing rooftop greenery increases the green coverage rate and enhances the value of a building. Environmental performance is rated under environmental performance assessment systems such as CASBEE and LEED, and introducing rooftop greenery increases social recognition.

One-shot column "Rooftop greening and asset value"

【Check More】
In recent years, rooftop greeningAs an effectIt is attracting attention
“Rainwater runoffSuppression"
"Green Infrastructure"

Green infrastructure is a concept that utilizes the diverse functions of the natural environment, such as the power and mechanisms that it possesses, to promote the development of social capital, land use, disaster prevention and mitigation plans, etc. The Ministry of Land, Infrastructure, Transport and Tourism defines it as "the development of sustainable and attractive nations and regions by utilizing the diverse functions of the natural environment (provision of habitats for living things, creation of beautiful landscapes, suppression of temperature rise, etc.) in both the hard and soft aspects of social capital development and land use."

Green infrastructure and stormwater runoff control greening facilities

Rooftop greening planning/design points

We will guide you through the points to be aware of when planning and designing a green roof.

[Checkpoint 1] Load capacity conditions

The long-term load that can be placed on a roof is calculated by multiplying the seismic load by the roof area, and varies depending on the building's use and the type of rooftop greening. The live load determined by the Building Standards Act is as shown in the table below. The weight of soil and drainage materials is calculated based on their weight in a wet state. The weight of trees must be taken into account along with the materials. It is important to plan with the growth of trees in mind.

Target	Housing	Department stores, etc.	The office
Floorboards	180kg / m²Above	300kg / m²Above	300kg / m²Above
Beams, columns, foundations	130kg / m²Above	240kg / m²Above	180kg / m²Above
Seismic Load	60kg / m²Above	130kg / m²Above	80kg / m²Above

Table 1: Live load (Article 85 of the Building Standards Act)

Specific gravity of natural soil:Around 1.6 to 1.8
Specific gravity of volcanic gravel:Around 0.8 to 1.4
Specific gravity of improved soil:Around 1.1 to 1.3
Gravel and sand specific gravity:Around 1.7 to 2.1
Specific gravity of lightweight soil:Around 0.6 to 1.0
Specific gravity of deck material:Around 0.9
Specific gravity of obsidian barite:Around 0.2
Brick specific gravity:Around 2.0
Wet specific gravity of pearlite barite:Around 0.6
Specific gravity of concrete:Around 2.3
Specific gravity of beet moss when wet:Around 0.8
Granite specific gravity:Around 2.8

Table 2: Specific gravity table of main materials used on rooftops
Source: "Q&A about Rooftop Greening You Need to Know," Urban Green Technology Development Organization, Special Greening Joint Research Group, published by Kashima Institute Publishing on December 2003, 12

Examples of plants suitable for rooftop greening

For more information on "Plants suitable for rooftop greening," please see the details page at the link below.

Plants suitable for rooftop greening

[Checkpoint 2] Check wind pressure resistance

When designing a green roof, the following measures are necessary to counter the strong wind pressure that occurs.

Check the wind pressure resistance of the rooftop greening installation surface (Article 82-XNUMX of the Enforcement Order of the Revised Building Standards Act).

When planning the layout of a rooftop greening system, keep in mind that wind pressure is greater on the periphery and corners of the rooftop compared to general areas.
The structure should be designed so that wind does not enter the bottom of the greening base from the edge.
The rooftop greening system should be fixed in place with a safety factor applied to withstand wind pressure.

High-rise building example
High-rise building example

With the revision of the Urban Renaissance Special Measures Act in 2011 and the designation of urban renaissance priority development areas across the country, high-rise buildings have been constructed one after another in urban areas. At the same time, securing green spaces has become important in redevelopment, and green spaces are often installed on the rooftops of skyscrapers over 200 meters in height, making it important to install safe, high-quality rooftop greenery.

One-shot column: "Points to consider when designing rooftop greenery on high-rise buildings"

[Checkpoint 3] Root-proofing measures and types of waterproofing layers

It is important to choose the most suitable waterproofing for your rooftop greenery, taking care to prevent mud curling (a phenomenon in which soil, sand, pollen, algae, etc. that has accumulated on the waterproofing layer turns into mud due to rainwater, and when it dries, the mud that adheres to the surface of the waterproofing layer shrinks, cracks, and peels up, damaging the waterproofing layer). Even if you choose a waterproofing layer suitable for your rooftop greenery, plant roots may still reach the waterproofing layer. For this reason, it is important to choose a waterproofing layer with guaranteed root resistance and to install a reliable self-adherent root-resistant sheet and planting base container.

Plant roots that have penetrated the waterproof layer
Installation of root-proof sheets
Two-layered greening foundation

Daiflex waterproof

[Checkpoint 4] About irrigation systems

When planting greenery on a rooftop that is prone to drying out due to sunlight and wind, it is extremely important to provide the plants with the water they need, but hand watering takes a considerable amount of time and effort. To ensure efficient watering, we recommend installing an automatic irrigation system.

Sensor type (a unique irrigation system that can be applied to a two-layered planting base)

Rainwater detection and stress period (*) irrigation controller. *Programming to give plants periods of no water depending on the season.

This efficient irrigation leads to significant water savings throughout the year.
⇒This also leads to savings in running costs.
If an error occurs, a lamp on the control panel will flash. It is also possible to connect a signal line to a communications room, etc.
You can extract the operation history on a dedicated PC. (265 times)
⇒When an abnormality occurs, you can specifically analyze "what kind of problem occurred" and "when" it occurred, which allows you to investigate the cause and accurately plan future countermeasures.

Timer type (watering system applicable to general planting bases, wall greening, and outdoor greening)

A controller that manages irrigation schedules by registering irrigation times for each season using a calendar function

The timing of irrigation is programmed in advance, so running costs can be accurately estimated.
⇒On the other hand, since the plants are irrigated even when they do not need it, the amount of water used (= running costs) is higher than with the sensor-type system.
If you have a battery-powered controller, you must remember to change the batteries.

[Checkpoint 5] Has it been evaluated by a public institution?

When selecting a rooftop greening system, it is important to check the product's structure, materials, and performance from various perspectives. However, because there are a wide variety of structures and materials for rooftop greening systems, there are many products, and each product has different performance and features. Having some sort of criteria to consider when making a selection makes it easier to consider.

We will introduce third-party certification systems that can be used when selecting a rooftop greening system. Checking whether a product is certified beforehand makes it easier to choose a safe and reliable product.

Quality and performance evaluation of building materials and equipment (Public Buildings Association Quality and Performance Evaluation Products)

By undergoing evaluation through this project, which is run by the Public Buildings Association, a general incorporated association, you can prove that your building complies with the standard specifications for public building construction.
In order to receive the evaluation, not only the product's performance is evaluated, but also its track record of use for more than three years and its after-sales service system.

Points to note when installing rooftop greenery

When constructing, it is important to check the following points:

unloading: A major point in rooftop greening construction is the unloading of the equipment. In the case of a new building, the unloading time depends on the construction process, such as dismantling scaffolding and cranes, so it is important to confirm the unloading time.
Also, if the plants are unloaded too early in the construction process, there is a high risk that they will wither, so care must be taken not to unload the plants until all construction is complete and water is coming out.
Primary water supply, Presence or absence of power supply: When installing an irrigation controller, it is necessary to check the controller's power supply and water supply equipment. Immediately after planting, plants need to be watered thoroughly to help them take root, so it is important to install the controller after water and electricity are supplied to the roof.

Maintenance of rooftop greenery

Rooftop greening requires the same planting management and water supply as outdoor greening. If left unmanaged, weeds will grow and plant roots will grow, risking adverse effects on the waterproofing layer. Furthermore, if left unmanaged, dead leaves and soil will fly away, which in the worst case scenario could lead to an accident where the greening system is blown away.
Therefore, it is important to prepare a maintenance plan in advance, including regular inspections and safety inspections of the irrigation controller, and confirm it with the manager.

Typical maintenance contents

Weeds will inevitably appear due to wind or seed blowing. If weeds do appear, they must be removed before they can grow large. Regardless of your maintenance schedule, remove weeds as needed.

Pruning depends on the type of plant, but just like with exterior plantings, they are managed separately for medium- to tall trees, shrubs and ground cover plants, and grasses.
When selecting plants, it is a good idea to consider the level of care required.

Plants can sometimes be prone to large infestations of caterpillars and cutworms, which eat away at the leaves and roots. If the infestation is discovered early, spot management is possible, but planned pest control throughout the year is more effective.

Weeds will inevitably grow, so regular spraying of pesticides will help control the weeds and keep them from overgrowth.

Fertilizing the plant appropriately in early spring will help ensure steady growth.

KYODO KY-TEC's strengths and product lineup

KYODO KY-TEC's Strengths

With a proven track record of over 2,000 projects, we offer a variety of rooftop greening systems, including our proprietary sensor-based automatic irrigation system. Here we introduce the benefits of adopting a rooftop greening system from KYODO KY-TEC.

From planning proposalsconstruction,Up to maintenanceWe provide total support

With a wealth of experience spanning over 2,000 projects, KYODO KY-TEC offers 1) safe and secure greening products, 2) extensive experience and the latest technology, and 3) appropriate design and consulting proposals.
We hope to continue to meet various needs in the future, such as rooftop greening for skyscrapers over 200 meters high, green infrastructure products to counteract sudden heavy rain, and rooftop greening that takes biodiversity into consideration."Environmentally friendly" greening products for a decarbonized societyWe aim to provide safety, security and the latest technology.

Cost control
making the plan
Construction management
Technical Support
Design and layout
Planting proposal/selection
Rooftop greening accessories
Appropriate product proposal/selection
Appropriate maintenance suggestions

Sensor-based automatic irrigation system: The "sensor-type automatic irrigation controller" is a unique rooftop greening management system developed using our proprietary technology that can detect rainwater and includes a stress period (programming to give plants periods of time without watering depending on the season).It offers various benefits, such as reducing the labor required for management and reducing running costs.
Product structure that allows for free design: With typical modular rooftop greening, plants are planted according to the dimensions of the unit, which means there are design restrictions such as size. However, KYODO KY-TEC's products are not modular, and the structural characteristics of the product allow for planting in both three dimensions and two dimensions, allowing for the free design of rooftop greening with a rich range of expression.
Responsible construction by specialized teams: KYODO KY-TEC not only sells products, but also takes responsibility for the construction work once an order is placed, providing a variety of one-stop product-related services, from proposals to delivery.
Support for maintenance after installation: If proper maintenance is not carried out, it could affect the asset value of the building. Therefore, we provide various maintenance support to customers who adopt our greening products so that they can use our products for a long time.

Sensor-based automatic irrigation system
Free design is possible
Responsible construction by specialized teams
Support for maintenance after installation

Product Lineup

KYODO KY-TEC's extensive product lineup is sure to meet your rooftop greening needs and circumstances.

What is rooftop greening?

What is rooftop greening?

For successful rooftop greeningPoints and
Important points to note during construction